Currently, a system is under study in which pluralities of modulation schemes, modulation bandwidths, and user channels are handled by an identical signal processing circuit, with progress of diversification and advanced features of a wireless communication system. A technique which combines a digital signal processing circuit and a switch which switches signal-processing paths is proposed as one method of such schemes.
A conventional multimode transmitter apparatus has been provided, which included two modulating sections modulating identical signals, and a plurality of transmitting sections including different paths and antennas (for example, refer to Patent Literature 1). The apparatus described in Patent Literature 1 connects these two modulating sections and a plurality of transmitting sections by a selector, and adjusts frame timing of a modulating section according to the delay amount of the transmitting section. Accordingly, the multimode transmitter apparatus described in Patent Literature 1 has an effect which maintains the delay amount of the overall apparatus constant, as a function.
FIG. 1 illustrates the conventional multimode transmitter apparatus described in Patent Literature 1.
With the conventional multimode transmitter apparatus illustrated in FIG. 1, in the case where a mobile station performs a soft handoff, identical signals generated in a base station pass through modulating section 13A and modulating section 13B, and are transmitted from two antennas through different paths. At this time, control section 11 adjusts a delay, due to a difference of signal paths, between a digital circuit provided in previous stage of selector 14, and an analog circuit provided in a subsequent stage of selector 14. Control section 11 causes clock generating section 17 to generate a frame clock considering signal delay, and adjusts signal supply timing according to signal paths to modulating sections 13A and 13B.